"waste from regular units"?

All zeolite systems re-generate and discharge the saline water. That's not a problem. The problem for me was the frequency of the regenerate cycle. The unit did it like twice a day which meant I always had lots of salt in the water. I plug it in once a month and I'm much happier. I add Iron-Out to the salt to get rid of iron build up.

There is a softener available that supposedly uses no salt BUT my softener uses no salt the filter is what uses the salt. The softener is passive, merely bubbling the acidic water through a limestone bed.

Not if the calcium is in solution. Dissolved minerals will flow through any mechanical filter.
The only ways I know to get 'em out are:
1.) Distillation
2.) Reverse osmosis
3.) De-ionization ( zeolite filtration with salt regeneration)
4.) kidney stones. Oops that gets 'em out too late.

As an aside one of the main causes of clogged pipes is MIXED METALS~!!

If you c have steel or steel with zink coated pipes in the same system as brass or copper you will get your pipes clogged so badly that eventually the water won't flow at all
The Galvanic action that arises from the combination of dissimilar metals and the minerals in water will cause metal molecules to sublime off from from one pipe type and settle on the other eventually creating a total blockage.

So you might think about whether you have dissimilar metals in your piping.

If you do - - I think you should get a second opinion on the water treatment, because you may not need a water treatment system at all. Just get rid if the steel pipes.